Hi, purplegreen, welcome!

I also had quite a lot of dreams dealing with people from the past (namely the middle school). Over a month or so, through affirmations, I turned that experience into an incredibly effective dreamsign - it brings lucidity over 95% of the time.

Affirmations are as follows:
"I've graduated middle school, I don't have to take any more Math or History classes ever again. Therefore if I ever find myself in a Math or History class, I would instantly recognize that I'm dreaming and become lucid" Repeated a few times before bed, with as specific details as possible, emphasizing the logical reason why this should make you lucid.

It's pretty cool, because now, 7 years later if I have similar dreams, I instantly become lucid.